Wallis company manufactures only one product and uses a standard cost system. the company uses a predetermined plantwide overhead rate that relies on direct labor-hours as the allocation base. all of the company's manufacturing overhead costs are fixed—it does not incur any variable manufacturing overhead costs. the predetermined overhead rate is based on a cost formula that estimated $2,889,000 of fixed manufacturing overhead for an estimated allocation base of 288,900 direct labor-hours. wallis does not maintain any beginning or ending work in process inventory.